Regulatory Effects of Lactobacillus crispatus and Lactobacillus rhamnosus on the Formation and Composition of Gardnerella Biofilms

Bacterial vaginosis (BV), the most common lower genital tract infection among women of childbearing age, is characterized by a decline in <i>Lactobacillus</i> populations and the excessive proliferation of anaerobic bacteria. Clinically, metronidazole remains the first-line therapeutic agent. However, the increasing recurrence rate has become an urgent clinical challenge. An important factor of BV recurrence is the persistent presence of <i>Gardnerella</i> biofilms, which enhances pathogenic resistance to antibiotics. In contrast, a healthy vaginal microbiome, predominated by <i>Lactobacillus</i>, exerts protective effects by producing antimicrobial compounds that inhibit BV pathogen colonization and restore microbial homeostasis. Given this, <i>Lactobacillus</i> preparations have gained widespread attention for their adjunctive therapeutic potential in BV management. Accordingly, in this study, we selected two extensively investigated <i>Lactobacillus</i> species, <i>Lactobacillus crispatus</i> and <i>Lactobacillus rhamnosus</i>, to evaluate their inhibitory capacity against <i>Gardnerella</i> biofilms. Our findings suggest that hydrogen peroxide and D-lactic acid are prominent bioactive components involved in the inhibition of <i>Gardnerella</i> biofilm formation by these <i>Lactobacillus</i> species, though the potential contribution of bacteriocins and other uncharacterized factors cannot be excluded. Notably, this inhibitory activity is not accompanied by alterations to the composition of pre-formed biofilms. This study clarifies the anti-biofilm mechanism of specific <i>Lactobacillus</i>, providing a valuable reference for future research on probiotic-based strategies for the treatment of BV.